Conventional methods of chemically treating fibers as in U.S. Pat. Nos. 1,635,865 and 2,868,005 and the currently made PETRIE/Wira Wool Scourer treat a mass of fibers by impacting such mass with impellers in a mass of liquid to drive fibers into the liquid while this process and apparatus provide for treating individual fibers by kneading actions on individual fibers while separated from the remainder of the mass of fibers and thus drive liquid into fibers and so impregnate such fibers with chemical-containing liquors.